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Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
Pregnant women usually experience a heightened sense of smell beginning late in the first trimester. Some experts call this the body's way of protecting a pregnant woman from foods that are unsafe for the fetus.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.